As the AFS proposed in order to improve the traveling safety of an automobile, there is a technique described in a Japanese patent document, JP-A-2002-160581. As shown in the schematic diagram of FIG. 1, an automobile CAR is provided with a steering sensor 1A for detecting a steering angle of a steering apparatus and a vehicle speed sensor 1B for detecting a vehicle speed. The detection outputs of these sensors 1A, 1B are inputted into an electronic control unit (hereinafter referred to as ECU) 2. The ECU 2 controls the irradiation area, e.g., the irradiation direction of head lamps (or headlights) 3 (swivel type lamps 3R, 3L) provided at the right and left front portions of an automobile so as to deflect in the left and right directions based on the detection outputs thus inputted thereby to change the light distribution characteristics. According to the AFS, when an automobile travels on a curved road, it is possible to deflect the irradiation direction of the swivel type lamps in accordance with the steering angle of the automobile to illuminate the portion of the road ahead of the curve, thereby being effective in improving traveling safety.
In such an AFS, when the left 3L and right 3R swivel type lamps are controlled so as to deflect merely in accordance with the steering angle, there arise various kinds of inconveniences. Various trials have been performed in order to eliminate such inconveniences. For example, a Japanese patent document, JP-A-62-244735, proposes a technique in which the timings of the deflection operations of left and right swivel type lamps with respect to the steering angle are differentiated in order to secure irradiation areas in the steering direction and the direction opposite thereto at the time of steering to the left or right, thereby to improve the visibility in a wide area. In this case, for example, at the time of steering to the right, the right swivel type lamp is deflected prior to the deflection of the left swivel type lamp. Then, when the steering angle reaches a certain angle, the left swivel type lamp is deflected to the right.
As described above, in the technique disclosed in JP-A-62-244735, since the timing of the deflection operation is differentiated between the left and right swivel type lamps, it is advantageous that the irradiation range of the lamps is enlarged. However, according to this technique, when the steering angle exceeds a predetermined angle, the deflection angles of the left and right swivel type lamps become equal to each other and so the lamps are directed to the same direction. Accordingly, when both the left and right swivel type lamps are deflected, an area in the straight traveling direction of an automobile is not irradiated sufficiently, so that it is difficult to confirm the safety in the straight traveling direction and so not preferable from the view point of traffic safety. Further, according to JP-A-62-244735, the deflection angle of the left and right swivel type lamps are changed according to the stepwise characteristics in correspondence to the change of the steering angle. Thus, there likely arises a condition when the deflection angle is unstable around the steering angle near the boundary of the step portion, so that the irradiation range vibrates to the left and right thereby to make a driver feel worrisome.
Accordingly, an advantage of the invention is that it provides a vehicle lighting apparatus which can suitably irradiate the steering direction at the time of steering to the right or left and also can suitably irradiate the straight traveling direction of an automobile.